The invention relates to a lock for a door or tailgate/gate with a catch mechanism comprising a rotary latch and a pawl for latching the rotary latch. Such a lock is, for instance, known from DE 103 20 457 A1.
The aforementioned lock allows temporary locking of openings in motor vehicles or buildings with the aid of doors or tailgates/gates. In the closed state of such a lock, the rotary latch grips around the, in particular, bow-shaped locking bolt, which in case of a vehicle is generally attached to the car body. When the rotary latch reaches a locked position after having been pivoted from an open position by means of a locking bolt, the rotary latch is finally latched by means of the pawl. A blocking surface of the pawl abuts in this case against a blocking surface of the rotary latch, preventing the rotary latch from being pivoted back in the direction of the open position. The locking bolt can no longer escape the catch mechanism in the closed position. In the closed position, the metal blocking surfaces of the rotary latch and pawl are pressed against each other during latching.
For opening, the pawl must be moved out of its latched position. Once the pawl has been moved out of its latched position, the rotary latch rotates in the direction of the opened position. In the opened position of the rotary latch and thus in the opened position of the catch mechanism, the locking bolt can escape the lock. The door and tailgate can thus be opened again.
The rotating of the rotary latch in the direction of the opened position after the pawl has been moved out of its latched position can be caused by a sealing pressure of the respective door or tailgate or by a spring. Such a rotation can also be caused by the locking bolt out being pulled out of the catch mechanism.
Locks can contain two different latched positions of the rotary latch. The rotary latch can initially be latched in the so-called intermediate closed position and then, by continued pivoting into the closed position into the so-called fully closed position. Although a locking bolt cannot escape the catch mechanism in the intermediate closed position, the respective door or tailgate/gate is, however, not fully closed. Such a door or tailgate/gate is only fully closed, when the rotary latch is turned up to the fully closed position and is latched in this position.
The rotary latch and pawl are generally rotatably mounted on the base of a lock case. The lock case is generally made of metal in order to ensure a stable fixing. In addition, arrangements generally contain amongst other elements and for weight reasons, an existing lock housing including a lock housing cover, offering protection against dirt and moisture. The lock housing and lock case form an infeed section for the locking bolt into the catch mechanism or into the infeed slot of the rotary latch.
The above characteristics can be individually or in any combination part of the lock of the invention, unless something else has been expressly disclosed.
Where two blocking surfaces are pressed against each other for latching and dust settles on the surfaces, the forces required for opening the catch mechanism can increase with increasing age. To reduce the opening forces that can be generated by dust entering and settling on the blocking surfaces pressing against each other, such blocking surfaces of the rotary latch and pawl are made of metal. A normally used plastic coating is thus no longer required. Dust particles can, however, also cause said increase in opening forces when such metal surfaces are used, so that further measures are required.